U.S. stocks traded lower Monday, weighed down by a renewed slide in the price of oil, several key earnings reports and the Federal Reserve's statement all due later in the week.

Energy, financials and materials, were all lower by almost nine percent year-to-date as of mid-afternoon trade.

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Discussing whether it is the right time to buy stocks on the dip, David Lafferty, chief market strategist at Natixis, told CNBC's "Power Lunch" that investors must think long term, not short term, when committing new money to the marketplace.

"Values are at hand, but only if you are prepared to wait several weeks or months, not days. I think this pullback is a pretty good opportunity to invest in the equity markets. But remember, gains can't materialize overnight, you need patience," Lafferty said.

Longer term, Lafferty favors the high yield sector, including materials and energy.

"Corporate bond spreads, both investment-grade and high yield, haven't been this cheap since 2012. And if you want to attract yields without sticking your neck out too far, bet on the bank loan sector."

Lafferty's top regional bets remains outside the United States.

"Right now, I would lean towards Europe, particularly the financials and banks," he said. "Ex-Europe, parts of Japan. too. These are some good entry points because valuations have become more attractive."

Natixis Global Asset Management, with $865.9 billion assets under management, is a multi-affiliate organization that offers a single point of access to 20 specialized investment firms in the Americas, Europe and Asia. The firm ranks among the world's largest asset managers.